These Forgefix Pozidriv Self-Tapping Screws are zinc plated for increased resistance to corrosion. Their Pan Head, with a flat under head surface makes the screw ideal to lay flat on sheet material of all types, thus reducing deformation. The screws tap their own thread in a pre-drilled pilot hole, in sheet metal. The screws are single threaded to resist pull-out. APPLICATIONIdeal for use in many DIY, ironmongery, engineering, electrical and plumbing applications. Zinc coatings prevent oxidation of the protected metal to create a longer lasting finish. It does this by forming a barrier and by acting as a sacrificial anode if this barrier is damaged. Zinc oxide is a fine white dust that (in contrast to iron oxide) does not trigger a breakdown of the substrates surface integrity as it is formed. The zinc oxide, if left intact, can act as a barrier to further oxidation, in a way similar to the protection afforded to aluminum and stainless steels by their oxide layers. The Pozidriv scr